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About Michael J. Miller

Miller, who was editor-in-chief of PC Magazine from 1991 to 2005, authors this blog for PC Magazine to share his thoughts on PC-related products. No investment advice is offered in this blog. All duties are disclaimed. Miller works separately for a private investment firm which may at any time invest in companies whose products are discussed in this blog, and no disclosure of securities transactions will be made.

Laptop Processors: Doing More With Less (Power)

You might think that processors hardly matter anymore, especially if you're interested in lightweight notebooks. After all, just about any current notebook can handle basic Web surfing and light word processing. When you start to do more complex work, though, it's clear that processors really do matter, as I found out while testing some spreadsheets on new laptops. I tested machines that were either running Intel's third-generation Core processors (known as Ivy Bridge) or AMD's second-generation A-series accelerated processing units (APUs).

Now, I've done a lot of this testing before, most recently looking at the quad-core Ivy Bridge chips as they first came out, and they impressed me.

This time, I tested one desktop replacement notebook running a 2.6GHz quad-core 45-watt Ivy Bridge chip (with four cores and eight threads), the Alienware M17, along with several thin laptops. The latter systems were running low-voltage processors. Two of them—the HP Envy 4 and the Lenovo Ideapad U310—were Ultrabooks running dual-core 1.7GHz Intel Core i5-3317U Ivy Bridge chips, with two cores and four threads rated at 17 watts. The other one was an HP Envy 6 Sleekbook running a new 2.1GHz AMD A6-4455M quad-core APU with four integer cores (running four threads) also at 17 watts.

Above: Envy 4, Alienware 17x, Envy 6, Ideapad U310

A few things to note: The AMD-based Sleekbook and the Ideapad both had 4GB of RAM, the HP Envy 4 had 6GB, and the Alienware had 8GB. This shouldn't matter as these tests do not take advantage of more than 4GB of memory. Also, recall that all of these systems actually can run faster than their native speeds through "turbo" modes depending on how hot the chips go. Finally, there may be a few errors in the results, given that Windows occasionally seems to do certain things on its own and my stopwatch skills are certainly not perfect. You should discount any differences of a second or less, or a couple percentage points of the total.

Here are my results:

As you would expect, the full-power 2.6GHz Quad-core Ivy Bridge clearly beats the low-voltage systems. That's no surprise because it's running at a higher clock speed with more cores and more threads, and drawing more power (45 watts versus 17 watts for the others). As I mentioned when I tested an earlier configuration of this system, this is a desktop replacement. These systems pretty much smoke every other notebook I've tested, but they are much bigger and heavier with 17-inch displays.

Among the thinner notebooks, the difference is enormous. The Ivy Bridge systems, which scored close to each other, were notably faster than the Trinity one—more than 50 percent faster in most cases. In one of the pivot table tests, it was more than twice as fast.

The Ivy Bridge systems were generally comparable to my tests of Sandy Bridge laptops, but the big difference is that the Ivy Bridge parts are 1.7GHz, 17-watt ones while the comparable Sandy Bridge part (a Core i5-2520M) is a 2.5GHz, 35-watt one, so Ivy Bridge should offer improved heat and battery life—important for the Ultrabook form factor.

The Trinity system also shows a reduced power consumption compared with the previous generation "Llano" APU (specifically the A6-3410MX), using 17 watts versus 45 watts, but carrying a nominal clock speed doesn't seem to matter much, as Trinity comes in behind the equivalent Llano part. On the other hand, the reduced power load does let it fit into much thinner designs, which AMD calls "ultrathins" and HP calls "Sleekbooks".

Note that although Intel has dramatically improved the graphics in Ivy Bridge over the Sandy Bridge generation, the AMD processors—especially the Trinity generation—has better integrated graphics still. That doesn't show up in these spreadsheet tests, but would matter if you wanted to play intense games.

Overall, the big difference between this year's dual-core Intel chips and AMD's laptop offering isn't more performance, it's providing similar performance with less power-hungry chips that can run in thinner machines. Still, the differences in performance are notable; Intel chips are still clearly much better performers than the AMD competitor and the quad-core Ivy Bridge is pretty much in a class by itself.

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